INSIDE CS Department of Computer Science SPRING 2007

then actively recruiting students we are I also want to congratulate Profs. Ramani especially interested in having attend Duraiswami and Atif Memon who were our program. Prof. Khuller spends an promoted this spring to the rank of As- enormous number of hours each spring sociate Professor and Adam Porter who semester on graduate student recruitment. was promoted to full Professor. With the It culminates in our annual visit day for departure of Heather Murray from our perspective students, and this year we had Graduate Office, we were fortunate to hire a record 30 students visit the campus to Jennifer Story as our Graduate Coordina- meet faculty and students and learn first tor. Jenny has been employed in various hand about our program. positions at the University since 1988. During the last eleven years, she was an Faculty recruiting this year focused on the Assistant Director for the University’s Notes from the Chair recently established Minker Professorship Honors Program. I also want to acknowl- and in the area of computational biology. edge all of those faculty, staff, and students by We were successful in hiring a new junior who participated in the Department’s faculty member in computational biology Awards Ceremony. Pictures from the Prof. Larry Davis (Carl Kingsford, a graduate of Princeton event and a copy of the program can be whose research will be described in our found on the department’s web page. The Spring 2007 semester is over, and fall newsletter), and are continuing our Finally, we want to acknowledge Profes- nearly 100 students received their B.S. de- search for the Minker Professorship. sor Emeritus Jack Minker who will be grees at the College graduation ceremony. celebrating his 80th birthday and 40 years Dr. Ravi Sethi, the CEO of Avaya Labs, A large anonymous gift, donated about a with the Computer Science Department. was the College commencement speaker; year ago to the Gannon fund, allowed us after the ceremony Ravi spent time meet- to significantly expand our undergraduate ing with faculty and graduate students in student scholarship offerings. The income the Department. from that fund is now used both to recruit Student Transportation excellent new students to our program, and While undergraduate enrollments in to reward our very best students for their Design Competition computer science are down nationwide, we outstanding academic performance. We have started to see an increase in new stu- are also using some of the fund’s income dents, thanks, in large part, to the vigorous to support first year graduate students recruiting activities of our undergraduate during the summer while they work on office led by Prof. Purtilo. We believe that research projects with faculty members. our success in recruiting new undergrads is Students were asked to submit propos- also due to the Passport program that Nel- als and a committee selected three of the son Padua-Perez has developed and grown strongest for this first summer. These especially during the past year. This students will give presentations this fall on spring semester we had over 200 middle their work. It is not too late to contribute and high school students come to the cam- to the fund – it really makes a difference pus every Saturday for instruction in com- in recruiting and retaining highly rated puter science at four different levels. Our undergraduate students and providing an department’s undergraduate enrollment is early research component in our graduate still more than twice the median for top program. Clockwise: Martin Stolen, Anna Nhan, Tiffany Gray and John Dobrosielski twenty computer science departments, ac- cording to recent statistics released by the I delivered the first “State of the Depart- Computing Research Association. ment” address in April. It gave me a With the demand on energy resources chance to thank many of the people who increasing as the supply decreases, energy While undergraduate enrollments are have contributed to the department’s costs in the United States have been at an down, applications to our graduate pro- programs, and to bring everyone up to date all-time high. Despite these costs, conges- gram remain at high levels. We had over on department initiatives in research and tion is still steadily increasing. Carpool- 1200 applicants this year for only 35-40 education. The slides from that presenta- ing has for a long time been an option to new graduate student positions. There tion are available on the department’s web help reduce congestion, but commuters is a significant amount of work involved page. currently under use it. The Carpool.UMD in evaluating so many applications, and website prototype started as a term project for CMSC 434 Hu- faculty members receive this honor each year. The award honors man Factors in Computer and Information Systems (http://www. senior faculty who possess a record of outstanding scholarly ac- cs.umd.edu/class/fall2006/cmsc434/), under the supervision of complishment, combined with excellence in teaching. Professor Ben Shneiderman. Samir is internationally recognized for his research in design- It is a social-networking website designed to make carpooling to ing efficient graph theoretic algorithms that can be used to solve and from the University of Maryland, College Park easier. The optimization problems from different areas. Many problems in website allows users to search for carpools, learn more about other this area are NP Hard, so it is important to develop provably gooy riders and manage their carpools. Carpool.UMD aims to create a approximate algorithms for these problems. One of Samir’s most safe and friendly community as well as making it convenient to well known results concerns research on a fundamental network carpool to and from the University. design problem call Light Approximate Shortest Path Trees. This work shows how to obtain a smooth tradeoff between spanning A project paper was entered in the Student Design Competition of tree weight and distance. In addition, the research he conducted on the Computer-Human Interaction (CHI) 2007 Conference held in Connected Dominating sets has been widely used in the wireless San Jose, California (www.chi2007.org). Carpool.UMD was one networking community and formed the basis of ad hoc network of 12 teams, out of 54 teams from around the world (19 different routing methods in wireless systems. schools in 11 countries), that were selected to present a design in the final stage of the competition. The conference took place from Samir is also passionate about teaching. He has worked closely April 28 to May 3, 2007. The team consisted of three Computer with some of our brightest campus and area high school students. Science Seniors; John Dobrosielski, Anna Nhan and Tiffany Gray, Undergraduate students have said that Prof. Khuller “got them as well as one Aerospace Engineering graduate student, Martin excited” about theoretical computer science. He taught them Stolen. about “patience and hard work”. He is seen as a “very enthusiastic researcher” who gives “clear presentations, full of exciting prob- Team members presented their project to an audience on Monday, lems”. He is a “wonderful human being and scholar, an embodi- April 16 in the CSIC Lecture Hall. A reception was held prior to ment of hope, energy and great ideas” and “he has helped us grow their presentation. into something better and beyond ourselves without any sense of effort.” The Departments of Computer Science, Transportation, and Aerospace Engineering provided financial support so that team One of Samir’s students, An Zhu, won the Dorfman Award for Un- members could attend the competition in California. We are all dergraduate Research then attended Stanford where she earned a very proud of the students and wish them success at the Confer- Ph.D degree. An is now with Google. Jessica Chang was selected ence and in their professional careers upon graduation. as a Phillip Merrill Presidential Scholar and identified Samir as one of the teachers that most influenced her. Samir continues to work with high school students from Montgomery Blair. In 2004, Michael Forbes was a finalist for the Intel Science Talent Pro- Professor Samir Khuller gram. This year, Matt McCutchen has conducted some impressive research which he plans to publish next year. Wins Prestigious Samir graduated from The Indian Institute of Technology in Distinguished Scholar-Teacher Kanpur, India in 1986. He received his B. Tech. degree from the Computer Science and Engineering Department and later earned Award his Ph.D. at Cornell University in 1990. In 1992, he was ap- pointed an Assistant Professor in the department after spending two years in UMIACS as a postdoctoral scientist. He received an NSF CAREER Award in 1995, a Lilly-CTE Teaching Fellowship in 1997, and the 2003 ACM PODS Best Newcomer Paper Award. He was promoted to full Professor in 2004. Samir’s publishing and department service records are outstanding. Along with his many other contributions, Samir is currently our Associate Chair for Graduate Education.

The Department is very proud of Prof. Khuller’s accomplishments and appreciates his hard work, dedication, and commitment to high academic and intellectual standards. No doubt his professo- rial visibility and career will continue to grow.

The campus has selected Prof. Samir Khuller to receive a Distinguished Scholar-Teacher Award for 2006-2007. Only a few CS 2 The Scientific Computing Group equations. The Fast Multipole Algorithm and Applications The motivation for fast multipole algorithms is to develop an efficient algorithm for computing the potential function for a set of charged particles. Dense matrices derived from point distribu- tions of data arise commonly in applications. The fast multipole method can be used to speed up matrix vector products and iterative solvers involving matrices with such structure. We are exploring the application of fast multipole algorithms to diverse problems including the biharmonic equation, Laplace equation, the Helmholtz equation, radial basis function fitting, Maxwell’s equa- tions, and to various kernels that arise in computational machine learning (Gaussian, logistic function, the logit kernel). Research is also focused on developing different data structures, other than Ramani Duraiswami, G.W. Stewart, Howard Elman and Diane O’Leary the standard ones used in the FMM, and on the development of preconditioners that can be easily implemented in the context of the FMM.

Numerical analysis and scientific computing have a long history Optimization in our department, dating from the work of Werner Rheinboldt and Numerical optimization methods are used to find the fastest, or colleagues in the 1970’s on the numerical solution of nonlinear least expensive, or most lowest energy solutions to problems in ar- equations. The group has always had close ties with numerical eas ranging from finance to protein folding. Some of our research analysts in the Mathematics Department, and our students are focuses on the efficient use of linear algebra in optimization; some drawn from the Applied Mathematics and Scientific Computing exploits structure in the optimization problem in order to devise Program as well as the Computer Science Department. Alumni more efficient algorithms. Recent work concerns the solution of include Xiaobai Sun (Duke), Robert van de Geijn (Texas), Yuan- conic convex optimization problems. Jye Jason Wu (Boeing), and Tamara Kolda (Sandia). Four faculty members currently work in the area of numerical analysis and The Solution of the Convection-Diffusion Equation scientific computing: Models of convection and diffusion are among the most wide- spread in science and engineering, with applications such as semi- • G. W. Stewart conductor modeling and transport of pollutants or heated fluids. • Howard Elman Discretization and numerical solution of such problems is compli- cated by the presence of steep gradients (boundary layers) in parts • Dianne O’Leary of the solution. We have developed efficient solution strategies • Ramani Duraiswami based on multigrid and have analyzed the effects of stabilizing dis- cretization strategies on accuracy an on performance of numerical Our research ranges from answering basic questions about numeri- solution algorithms. cal algorithms, to applying numerical techniques to a diverse set of applications. We give brief summaries of some of our work Solution of Ill-Posed Problems & Image Deblurring below. In ill-posed problems, small changes in the data can cause arbi- trarily large changes in the results. Although it would be nice to Matrix Eigenvalue Problems avoid such problems, they have important applications in medicine Eigenvalue analysis is used, for example, to determine resonant (computerized tomography), remote sensing (determining whether frequencies of musical instruments, stability of control systems a nuclear reactor has a crack), and astronomy (image processing). for automobile braking, and flight characteristics of airplanes. Our work has focused on studying the characteristics of solutions Our work has produced fundamental understanding of the effects produced by various regularization methods, especially iterative of perturbations on the eigenvalues and eigenvectors of matrices. methods for large problems. We have proposed efficient numerical Most recently, our focus has been on development of Eigentest, a algorithms for image deblurring. test matrix generator for large-scale eigenproblems, and a residual Arnoldi method for solving these problems. Solution Algorithms for Models of Incompressible Flows The Navier-Stokes equations are of fundamental importance Solution of Large Linear Systems of Equations for modeling of incompressible flows. Discretization leads to a In one study of numerical software, it was determined that 90% coupled system of nonlinear algebraic equations for velocities and of the subroutine calls accessed solvers for linear systems of pressures. By taking advantage of the special structure of the dis- equations. This is an important problem in its own right, but also crete problem and building on algorithmic advances achieved for a component of algorithms for more complex problems such as individual scalar subproblems, we have developed new solution solving nonlinear equations and partial differential equations, so algorithms that are generally applicable to steady-state and evolu- efficiency is key. We study iterative methods such as GMRES and tionary problems and display convergence rates largely insensitive the conjugate gradient algorithm for solving large linear systems. to fundamental problem parameters such as discretization mesh In particular, we develop preconditioning techniques to speed the size and Reynolds number. Ongoing research in this direction solution of certain problems arising in the solution of differential includes the extension of these ideas to solve the eigenvalue prob- CS 2 CS 3 lems that arise from stability analysis of steady-state solutions. James A. Hendler Accepts Position at Computing with Uncertainty Rensselaer Polytechnic Institute Traditional methods of mathematical modeling depend on the assumption that components of models such as diffusion coef- ficients or boundary conditions are known. In practice, however, such quantities may not be known with certainty and instead they may be represented as random functions, that is, a random variable for each point in the physical domain. An approach for perform- ing computational studies of models of this type is the stochastic finite element method, which is a generalization of finite element discretization for deterministic problems designed to handle prob- lems posed with uncertainty. We have explored this methodology to model elliptic partial differential equations when some terms in the problem are not known with certainty, and we have developed efficient algorithms for solving the associated discrete problems.

Information Retrieval In spite of the fact that more than 600,000 medical papers are pub- lished annually, physicians are expected to be familiar with current literature ranging from the common cold to cancer. Researchers in a variety of fields face similar challenges. The aim of our research r. James Hendler, a Professor in the department for the past in information retrieval is to develop tools, based on linear algebra D twenty years, accepted a position as Senior Constellation Professor and optimization, that retrieve documents that are relevant to a at Rensselaer Polytechnic Institute effective January 1, 2007. RPI user’s query and provide contextual summaries of these docu- Constellations focus on a specific research area and comprise a ments. multidisciplinary mix of senior and junior faculty and postdoctoral and graduate students. Jim holds appointments in both the Com- Medical and Biological Applications puter Science and the Cognitive Science Departments at RPI. He The structure of a protein provides critical information in deter- also serves as the Associate Director of the Web Science Research mining its function. Our recent work includes development of a Initiative headquartered at MIT. new algorithm for determining the shape of a protein and a fast screening algorithm for finding proteins whose structure is ex- As Chair of the Tetherless World Research Constellation, a Center pected to be similar to one presented for classification. to direct the “Future of Information” Project, Prof. Hendler is conducting research on increasing access to information at any Quantum Computing time and place without the need for a “tether” to a specific com- Quantum computers may offer a way to solve certain problems puter or device. He and other researchers envision an increasingly that are larger and more complex than any that can be solved on Web-accessible world in which personal digital assistants (PDAs), conventional computers. One way to view a quantum computer cameras, music-listening devices, cell phones, laptops, and other is as a machine that multiplies a vector by a unitary matrix. Our technologies converge to offer the user interactive information work in this area focuses on several questions relevant to the and communication. Jim also plans to continue his work in Web decomposition of the unitary matrix into quantum ``gates” that can Science, guide interdisciplinary research, and enhance information actually be made to work. technology, computer science, and cognitive science programs. Scientific Computing on Graphics/Game Architectures Rensselaer’s President Shirley Ann Jackson said in a press release, Architectures such as Graphical Processing Units (GPUs) or Cell “Dr. Hendler’s intellect and scientific leadership are evident in Processors are application specific and have seen a tremendous his pioneering work to extend the reach of the World Wide Web. improvement in their capabilities over the past decade, while at the He is actively engaged in both scientific discovery and public same time being relatively inexpensive. While their primary use is discourse on Web-related technologies. As leader of the Tether- for graphics and gaming, our research attempts to use them in an less World Research Constellation, he will guide interdisciplinary heterogeneous environment including these processors and research and enhance information technology, computer science, and cognitive science programs at Rensselaer.” CPUs to speed up algorithms in linear algebra, interior point meth- ods, image processing, audio processing, and the fast multipole Prof. Hendler received a Bachelor’s Degree in Computer Science method. and Artificial Intelligence from Yale University, a Master’s Degree in Cognitive Psychology and Human Factors Engineering from Southern Methodist University and a second Master’s Degree and Doctorate in Computer Science and Artificial Intelligence from Brown University. Upon receiving his Ph.D., he began his academic career at the University of Maryland as an Assistant Pro- fessor. Prof. Hendler, a renowned computer scientist and World Wide Web researcher, has amassed a long list of accomplishments

CS 4 during his career. Jim has authored one book and more than 200 major AI conferences. Many thanks to Lise Getoor and Don Per- technical papers in the areas of artificial intelligence, Semantic lis, graduate students Galileo Namata, Gerardo Simari, Amy Sliva, Web, agent-based computing and high performance processing. Vanina Martinez and Shomir Wilson, and support staff Brenda He is a Fellow of the American Association of Artificial Intelli- Chick and George Pelham, who put the day together. The event gence, a member of the World Wide Web Consortium’s Semantic was a great success with over 100 faculty and students participat- Web Coordination Group, Editor-in-Chief of the journal IEEE ing in the event. Intelligent Systems, and a reviewing editor for the journal Science, the first computer scientist ever to serve on its board. Jim was a past recipient of the Fulbright Foundation Fellowship in 1995, a former Chief Scientist of the Information Systems Office at the U.S. Defense Advanced Research Projects Agency (DARPA), and TRIVIA QUIZ a former member of the U.S. Air Force Science Advisory Board. He was awarded a U.S. Air Force Exceptional Civilian Service 1. Which two CS professors at UMCP also got Medal in 2002. their Ph.D.s here? Widely recognized as one of the inventors of the ‘Semantic Web’, Jim says, “this extension of the World Wide Web will bring new 2. Who discovered games such that the more information resources which will enable computers to interpret you know, the worse you play? the meaning and context of words and numbers. This technology could be used to bring informative databases – from Internet busi- ness to basic biology research – to the Web in more searchable and 3. Who was the first chairman of our depart- usable ways. While modern science has grown in complexity and ment? scope, there is an increasing need for more collaboration between scientists at different institutions, in different sub-areas, and across 4. What AI professor has received an award for scientific disciplines. The current World Wide Web supports scien- his work on human rights? tific research to a great extent, but is insufficient for the needs of collaboration across scientific disciplines. 5. What AI professor headed an eponymous The Semantic Web also provides a common framework that al- company? lows data to be shared and reused across application, enterprise, and community boundaries for the non-scientist. There are lots of data used every day, which are not part of the web. One can 6. What professor has both a Ph.D. and an view bank statements, photographs, and calendar appointments M.D.? but can not see photos in a calendar so that one knows what we were doing when we took the photo or see a bank statement in a 7. What AI professor has two Ph.D.s? calendar because we don’t have a web of data. Data is controlled by applications, and each application keeps to itself. The Semantic Web allows a person, or a machine, to start off in one database, 8. What AI professor has a Ph.D. graduate who and then move through an unending set of databases which are is an NSF PCASE awardee? connected not by wires but by being about the same thing.” 9. Which CS professor went to ground The Department is very proud of Prof. Hendler and his accom- school for a pilot’s license? plishments. A reception was held on May 2 to officially thank Jim for his many years of work at UMD and to wish him much success in his career at RPI. Jim and his family will be moving to New 10. Which CS professor’s thesis advisor was York in July 2007. instrumental in the development of the internet?

11. Which CS professor was Chair of the ACM AI Research Day Computer Science Education Committee which wrote the famous report on Computer Science The Department’s first ever AI Day was held on April 27. The Education at the college/university level? day was designed to give graduate students, especially our new graduate students, an overview of our AI research program. The day started off with short presentations by many of our AI faculty. 12. Which CS professor’s MS advisor was the Students, researchers, and faculty heard about research in machine postdoc advisor of her Ph.D advisor? translation, automatic reasoning, cognitive neuroscience, com- puter vision, machine learning and other topics. There was an entertaining intermission in the midst of the talks during which the (Answers: 1.Larry Davis, 1976; Jim Reggia,1981 2. Dana Nau, pathological games 3. Jack audience took an AI trivia quiz (portions reproduced below in case Minker 4.Jack Minker, AAAS Fellow 5.Laveen Kanal, LINK Corp. 6.Jim Reggia, MD in neu- rology 7.Don Perlis, CS and Math 8.Dana Nau (awardee, S.K. Gupta) 9. Bonnie Dorr 10.Hanan you’d like to try it). Lunch time was poster time, with over 25 Samet 11.William F. Atchison, Director of UMD’s Computer Science Center 12. Getoor; she did students presenting posters describing work they’ve presented at her MS w/ Stuart Russell, who was the postdoc advisor of her Ph.D. advisor, Daphne Koller.) CS 5 In The News...

Congratulations to Necip Fazil Ayan, who was a major contributor and second author on the “Best Paper” at the North American ACL-2007 this year. Fazil provided a novel phrase-level system combination approach for machine translation and also demonstrated that a combination of three approaches (word-level, phrase-level, and sentence-level) achieves the best result.

Jessica Chang was selected for Honorable Mention in the Computing Research Association’s Outstanding Undergraduate Award for 2007. This year’s nominees were a very impressive group. A number of them were commended for making significant contributions to more than one research project, several were authors or coauthors on multiple papers, others had made presentations at major confer- ences, and some had produced software artifacts that were in widespread use. It is quite an honor to be selected for Honorable Mention from this group. Congratulations, Jessica!

Over spring break, Dana Nau gave invited talks at two Chinese universities: Hong Kong University of Science & Technology and Sun Yat-Sen University (in Cantonese) or Zhongshan University (in Mandarin). During the visit, he discovered that a professor at the latter university is translating his book, Automated Planning: Theory and Practice, into Chinese.

Bill Arbaugh was quoted in “Computer Weekly” in an article about the rootkit problem. Malware writers are using the exact tech- niques that the security writers have been using for years in order to keep their software from being detected.

Allison Druin and the Human-Computer International Children’s Library were featured on “ABC News” on January 2 in a piece that focused on the design and testing of the Library’s interface for children’s books across digital media.

Professor Emeritus Jack Minker gave an invited keynote address,``Reflections on Logic Programming and Nonmonotonic Reason- ing,’’ at the International Conference on Logic Programming and Nonmonotonic Reasoning held in Tempe, Arizona, May 14 - May 17, 2007.

Dianne O’Leary was chosen as the winner of the College’s annual Board of Visitor’s award for 2007 CS 6